Construction of the fortress started in 1748 when Finland was still part of the Kingdom of Sweden. Sweden wanted to defend the sea areas against Russia. They also needed a place to fix their military ships. In 1808 Russia ruled Finland.[1] They made the fortress stronger to defend Helsinki, which was now the capital of Finland.[2]

In 1917 Finland became independent. In 1918 Viapori was taken over by the new Finnish government and was renamed Suomenlinna ( meaning "Castle of Finland").[1] Some of the islands were used as a navy school. There was also a prison, and prisoners worked to repair the old fortress.[2]

Today, Suomenlinna is one of Finland's most popular tourist attractions.[3] It is only a short ferry ride from Helsinki to visit Suomenlinna.[3] It is a Unesco World Heritage site.[2] It is also a living part of Helsinki city. Around 850 people live there.[2]